In contrast with the production of substituted phosphines wherein the substituents are aliphatic, the production of phosphines having aromatic substituents is frequently very difficult, depending on the particular phosphine desired. Particular difficulties often arise when mixed aryl-alkyl phosphines are desired.
The class of mixed aryl-alkyl phosphines is illustrated by the bis(diphenylphosphino)alkanes. Such bisphosphines have demonstrated and widespread utility as components of catalyst compositions which also include Group VIII metal compounds. One use of such catalyst compositions is in the production of linear alternating polymers of carbon monoxide and at least one ethylenically unsaturated hydrocarbon. These polymers have the repeating formula -CO--A-- A wherein A represents ethylenically unsaturated hydrocarbon polymerized through the ethylenic unsaturation. By way of further illustration, when the at least one ethylenically unsaturated hydrocarbon is ethylene, the linear alternating polymer is represented by the repeating formula -CO--CH.sub.2 -CH.sub.2 --. Illustrative methods for the production of such polymers are disclosed in Published European Patent Applications 121,965 and 181,014. The catalyst compositions therein described include compositions formed from a compound of a Group VIII metal such as a palladium carboxylate, the anion of a strong non-hydrohalogenic acid and a bis(phenylphosphino)alkane. The bis(diphenylphosphino)alkanes were particularly useful, especially bis(diphenylphosphino)propane. For other modifications of the polymerization process, bis(substituted-phenylphosphino)alkanes have been found to be useful, particularly 1,3-bis[di(2-alkoxyphenyl)phosphino]-propane. Such a process is described and claimed in copending U.S. patent application Serial No. 930,468; filed Nov. 14, 1986
One method of producing bis(phenylphosphino)alkanes is shown by U.K. Patent Application 2,101,601. This process involves a multi-step process employing a phosphonium salt as an intermediatre. An alternate process for the production is shown by Chatt et al, J. Chem. Soc. Dalton Trans., pp. 1131-1136 (1985). The Chatt et al process involves the use of a bis(dichlorophosphino)alkane, the production of which is said to require iron equipment which slowly degrades during reaction. A method described in copending U.S. patent application Serial No.07/175,021, filed Mar. 30, 1988
(Attorney's Docket No. T-0283) comprises reaction of a dihaloalkane and an alkali metal (di(alkoxyphenyl)phosphide produced by reaction of elemental alkali metal and the corresponding tri(alkoxyphenyl)phosphine. It would be of advantage to provide an alternate method for producing bis(alkoxyphenyl)phosphino alkanes.